Abstract Licania macrophylla is a medicinal plant from the Amazon. It is mainly used in the form of a decoction and has been reported to contain several phenolic compounds. However, the effect of seasonality on the phenolic composition and antioxidant potential of this plant has not been well studied, especially in the Amazon region, an area affected by the rainy and less-rainy seasons. Therefore, we evaluated the seasonality of these aromatic compounds and the antioxidant potential of the extracts from L. macrophylla stem bark. We also determined the correlation between the extraction methods used and precipitation levels during each period for 1 year. The total flavonoid and phenolic content, DPPH-scavenging potential, percentage of phosphomolybdenum complex reduction, and iron-reducing power were quantified. The levels of phenolic compounds were the highest in June, whereas those of flavonoids were the highest in September and October; however, these differences were not significant. The extracts from April, November, and June showed the best results for DPPH scavenging, phosphomolybdenum reduction, and iron reduction power, respectively. Significant differences in the phenolic content and DPPH-scavenging activity were observed between the more- and less-rainy seasons. The total phenolic content was positively correlated with FRAP and DPPH, whereas flavonoid levels were negatively correlated.